(1) Field of the Invention
This invention is concerned with an improved solenoid such as, but not limited to, solenoids which are used with ribbon lift devices of the type used in typewriters and printers. The invention also has application to other devices and apparatus which may utilize a solenoid of the plunger type wherein it is desired to reduce the increased plunger force that would otherwise occur during the plunger stroke.
(2) Description of the Prior Art
It is known in the prior art to provide means in a plunger-type solenoid to modify the plunger force characteristics that would otherwise occur during the plunger stroke. In such prior art devices, the force characteristics of the solenoid plunger stroke are modified to meet the particular requirements of the device or apparatus with which the solenoid is used.
One such example is the solenoid disclosed in U.S. Pat. No. 4,429,342 issued to U. Heider on Jan. 31, 1984 for an "Impact Printing Device with an Improved Print Hammer." This patent discloses a solenoid that is adapted to increase the speed of the print hammer operation in a printing mechanism and, as such, in contrast to the present invention, means are provided to increase the plunger force (and speed) during the solenoid plunger stroke.